The objectives of this project are: (1) to define the biochemical nature of the factors regulating cellular proliferation and death during palatal development. The importance that growth plays in palatal elevation is being tested. Precocious activation or inhibition of epithelial cell death involving altered DNA, glycoprotein and lysosomal enzyme synthesis is being tested with various agents such as cyclic nucleotides, steroids and growth factors. Isolated palatal epithelium and mesenchyme are being analyzed and cultured. (2) To determine the biochemical basis for interdigital cell death during normal mouse development and abnormal development in the mouse mutant-Hammertoe; (3) to determine the biochemical nature and role that surface glycoproteins play in normal and abnormal cell interactions during secondary palatal adhesion and neural crest cell migration. These studies will be carried out mainly in vitro visualizing the incorporation of labeled precursors into the surface with autoradiography and with biochemical analysis following release of glycopeptides with proteolytic enzymes. (4) To determine the source and function that hyaluronic acid plays in cranial neural crest cell migration and differentiation.